The proposed work involves 1) isolation and purification of growth hormone from pituitaries of pigeon, chick, and one (possibly 2) teleost fish; 2) further chemical and physical characterization of canine, porcine and bovine GH by progressive deamidation, to investigate the part that net charge may play in immunochemical and biologic specificity; 4) further work on the isolation of "high-prolactin" fractions of human growth hormone, in order a) to see whether a practical "pseudo-prolactin" low in growth activity can be prepared, which might have experimental or therapeutic utility and b) to try to understand the structural requirements for prolactin activity of hGH; 5) to complete studies on the isolation and characterization of porcine prolactin. BIBLIOGRAPHIC REFERENCES: "The nature of fragments of human growth hormone produced by plasmin digestion." Kostyo, J.L., J.B. Mills, C.R. Reagan, D. Rudman and A.E. Wilhelmi, Proc. III. International Symposium on Growth Hormone, Milan, Italy (Sept., 1975). "Assay of pig growth hormone preparations for metabolic activities in the rat and in man." Mills, John B., M. Zeringue, R. Harris, A.E. Wilhelmi and D. Rudman, J. Clin. Endocrinol. Metab. (1976), In Press.